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The first man to run a marathon in under two hours in 2019, Kenyan Eliud Kipchoge, had one thing in common with Marcell Jacobs, who won the gold medal in the 100m final at the Tokyo Olympics in 2021: carbon fiber shoes. Since these “super shoes” were put on the market they have revolutionized athletics at high levels, contributing to the accumulation of many new records and also provoking some debate. But they have also begun to be purchased by non-professionals attracted by the idea of being able to improve their performance, although they are not suitable for everyone.
The most famous carbon fiber running shoes are probably the Nike Vaporfly, like those used by Kipchoge during the 2019 Vienna marathon, in conditions which however did not allow his time to be recorded as an official record. Models like these have a sheet made of carbon inserted into the midsole, that is, the part of the shoe between the sole and the upper, but there are also some with some kind of carbon straws that follow the shape of the toes, like the Boston 10 by Adidas.
These shoes allow you to cushion the impact of each stride and thus reduce the dispersion of energy every time a foot touches the ground, essentially functioning as a kind of spring that pushes the wearer forward. For this reason, as shown by some studies, they improve the mechanics of movements and the effectiveness of running: in short, by wearing them you can take higher and longer steps, with less pressure on the feet and ankles. The result is that using carbon fiber shoes in the 42 kilometers and 195 meters of a marathon does not entail an advantage “of a few seconds or tenths of a second, but also of several minutes», noted in a recent article the Guardian.
Since the first prototypes of carbon fiber shoes began to be introduced in 2016, and especially since 2019, the consequences have been significant, particularly over long distances. Fourteen of the fifteen best times ever in the men’s marathon were set by people wearing them (obviously, being a permitted tool, practically everyone at the highest level now wears them); only one, established by Kenyan Dennis Kimetto in Berlin in 2014, predates their introduction.
In a 42 kilometer race there are many factors that determine performance, and it is also natural that with the progression of training techniques the athletes’ times improve. The accumulation of new records in the marathon, therefore, probably also has other reasons, and is not solely attributable to carbon fiber shoes. But there is little doubt about how much they had a decisive role: for example, in 2019 the Kenyan Brigid Kosgei – who wore them – set the new record for the women’s marathon by running the Chicago marathon in 2 hours, 14 minutes and 4 seconds : 81 seconds less than the previous record, held by the British Paula Radcliffe, which had remained unbeaten for 16 years.
Such a gap is an enormity for the discipline. With the improvement and updating of carbon fiber shoe models, and the parallel adaptation of athletes to their use, it has even been expanded. The record set in 2019 by Kosgei, who wore a model from the Nike Vaporfly era, was in fact beaten another four times in the following years, and the most recent, set in 2023 in Berlin by the Ethiopian Tigist Assefa (who instead had a pair of Adidas Adizero Adios Pro Evo 1), improved it by over two minutes.
Kelvin Kiptum, the Kenyan athlete who died last February in a car accident and holds the current world record for the men’s marathon, with 2 hours and 35 seconds, also run in Chicago in 2023, also wore carbon plate shoes.
The carbon fiber shoes are designed and designed for athletes who run at high levels, because to be able to fully exploit them you need to have a minimum amount of technique, run fast and support the forefoot above all, given that this is how you perform. the push. However, they are not recommended if you run little and slowly, as well as for those who weigh too much: yet they are having good commercial success even among amateurs who simply want to try to improve.
When the Nike Alphafly 3 that Kiptum had worn in the prototype version in October went on sale online in January, they sold out within minutes across Europe. In September, Adidas’ Evo 1s, which cost 500 euros or 400 pounds in the United Kingdom, were also sold out within a few hours, where in January they were put on the market again for 50 pounds more and on the secondary market they can also be found at 2,500. Nowadays all the most important sportswear brands have at least one carbon fiber model: not only Nike and Adidas, but also Puma, New Balance and Diadora.
Models like these have also changed the aesthetics of running shoes, which were previously rather minimal, while now in comparison they resemble Moon Boots, writes the Guardian citing the famous après-ski brand and alluding to the thick layer of foam they have under the heel. According to the rules of the World Athletics Federation, the sole of the shoe under the heel cannot be higher than 40 millimeters, and there cannot be more than one carbon plate inside it.
An athlete holds up his Nike Vaporfly shoes after finishing the Dubai Marathon in the United Arab Emirates on January 24, 2020 (REUTERS/Christopher Pike)
“There is no doubt” that if you are trying to improve a record in a marathon you would choose “a super shoe, because it allows you to save two minutes”, he also told the Guardian Andy Dixon, the magazine’s editor Runner’s World in the United Kingdom. For critics, using them is a bit like cheating, even if for World Athletics the advantage they give to those who use them cannot be considered “unfair”; those who appreciate them, however, claim that they can help make long and sometimes boring runs like marathons more captivating. Although they make running more effective, they still involve some risks.
As Jay Dicharry, physiotherapist and biomechanics researcher at the University of Oregon, noted, if you are composed during the run and have good control of the foot and ankle then these shoes can work: otherwise «a super shoe will significantly magnify the ‘instability’ of the wearer. Podiatrist Amol Saxena then recalled that the carbon plate does not adapt perfectly to all feet, with the result that in the long term it can cause discomfort or inflammation in some people. At the moment there is no evidence to say with certainty that these shoes cause injuries, but some studies have linked their use to stress fractures, plantar fasciitis, Achilles tendon problems and more generally to disorders of the foot and lower part of the leg.
However, even the majority of professional athletes tend to use them only during competitions and very little during training. “Obviously they make you go faster, which is a big advantage in the race,” said Rose Harvey, the fifth fastest British marathon runner of all time, who lowered her personal best by around five minutes by running in the Nike Vaporfly. «But the main advantage during training is just the recovery time», since they allow you to train intensely with a little less effort. «Before, after a marathon, I wouldn’t have been able to walk for a week. But after Chicago I was already running the next day, and my legs weren’t that bad.”
In any case, we tend to use them as little as possible both because they cost a lot, from 250-300 euros upwards compared to 150-200 for very good running shoes but without carbon fibre, and because the performance of the cushioning system drops more rush.
– Read also: Because so many sporting records have been broken during the pandemic
2024-04-14 12:16:09
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